feat: Production readiness improvements for WHOOSH council formation

Major security, observability, and configuration improvements:

## Security Hardening
- Implemented configurable CORS (no more wildcards)
- Added comprehensive auth middleware for admin endpoints
- Enhanced webhook HMAC validation
- Added input validation and rate limiting
- Security headers and CSP policies

## Configuration Management
- Made N8N webhook URL configurable (WHOOSH_N8N_BASE_URL)
- Replaced all hardcoded endpoints with environment variables
- Added feature flags for LLM vs heuristic composition
- Gitea fetch hardening with EAGER_FILTER and FULL_RESCAN options

## API Completeness
- Implemented GetCouncilComposition function
- Added GET /api/v1/councils/{id} endpoint
- Council artifacts API (POST/GET /api/v1/councils/{id}/artifacts)
- /admin/health/details endpoint with component status
- Database lookup for repository URLs (no hardcoded fallbacks)

## Observability & Performance
- Added OpenTelemetry distributed tracing with goal/pulse correlation
- Performance optimization database indexes
- Comprehensive health monitoring
- Enhanced logging and error handling

## Infrastructure
- Production-ready P2P discovery (replaces mock implementation)
- Removed unused Redis configuration
- Enhanced Docker Swarm integration
- Added migration files for performance indexes

## Code Quality
- Comprehensive input validation
- Graceful error handling and failsafe fallbacks
- Backwards compatibility maintained
- Following security best practices

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

vendor/github.com/mattn/go-isatty/README.md

@@ -0,0 +1,50 @@
+# go-isatty
+
+[![Godoc Reference](https://godoc.org/github.com/mattn/go-isatty?status.svg)](http://godoc.org/github.com/mattn/go-isatty)
+[![Codecov](https://codecov.io/gh/mattn/go-isatty/branch/master/graph/badge.svg)](https://codecov.io/gh/mattn/go-isatty)
+[![Coverage Status](https://coveralls.io/repos/github/mattn/go-isatty/badge.svg?branch=master)](https://coveralls.io/github/mattn/go-isatty?branch=master)
+[![Go Report Card](https://goreportcard.com/badge/mattn/go-isatty)](https://goreportcard.com/report/mattn/go-isatty)
+
+isatty for golang
+
+## Usage
+
+```go
+package main
+
+import (
+	"fmt"
+	"github.com/mattn/go-isatty"
+	"os"
+)
+
+func main() {
+	if isatty.IsTerminal(os.Stdout.Fd()) {
+		fmt.Println("Is Terminal")
+	} else if isatty.IsCygwinTerminal(os.Stdout.Fd()) {
+		fmt.Println("Is Cygwin/MSYS2 Terminal")
+	} else {
+		fmt.Println("Is Not Terminal")
+	}
+}
+```
+
+## Installation
+
+```
+$ go get github.com/mattn/go-isatty
+```
+
+## License
+
+MIT
+
+## Author
+
+Yasuhiro Matsumoto (a.k.a mattn)
+
+## Thanks
+
+* k-takata: base idea for IsCygwinTerminal
+
+    https://github.com/k-takata/go-iscygpty